Study On Halophytes Applied To Dry Drainage System

Soil salinization is an important factor affecting the sustainable development of irrigation districts.Dry drainage utilizing evaporation capacity of wasteland is a new method of the prevention and control of salinization in recent years.Planting halophytes on salt wasteland is an important measure to improve the dry drainage capacity of wasteland and prolong the operation of dry drainage system.Based on the Inner Mongolia Hetao Irrigation District,this paper discusses the salt tolerance,water consumption capacity of Tamarix Chinensis,Elaeagnus Angustifolia,Suaeda Aalsa and Phragmites Australis,and their regulating effects on soil water and salt movement.The method of constructing saline vegetation suitable for dry drainage system is also introduced,which provides technical reference for the design of dry drainage project.The main conclusions include:(1)The salt tolerance of the studied halophytes is: Phragmites Australis >Suaeda Salsa > Tamarix Chinensis > Elaeagnus Angustifolia.Salt tolerance of herbaceous halophytes is stronger than that of woody halophytes.However,in the zones where the soil salinity is less than 1.5%,herbaceous plants are prone to interspecific competition with woody plants,and their growth and population density are inhibited.The multi-level halophytes community of woody-herbaceous plant mixtures only exists in the soil with salt content less than 1.0% in the root zone.The morphological indexes and population density of the herbaceous plants are sensitive only to the salt content of 0-10 cm soil layer near the surface,while woody halophytes are sensitive to the salinity of 0-40 cm soil layer.(2)The regulating effect of halophytes on water and salt movement in soil is mainly manifested in the following aspects: through continuous transpiration,the soil water reserves in wasteland can be continuously consumed;through root water absorption,the soluble salts in soil can be accumulated in rhizosphere soil along with water movement.Compared with simple halophyte communities,the woody-herbaceous mixed zone has a better regulation effect on soil water and salt movement.It not only has a stronger ability to consume the water and accumulate the salt in the soil,but also can distribute the accumulated salt evenly in all soil layers,which improves the potential of salt storage in the wasteland and the sustainability of dry drainage design.(3)Compared with herbaceous plants,woody plants have strongerevapotranspiration and the ability to regulate groundwater and soil water dynamics.Transplanting halophytes can be used as a complementary measure in the design of dry drainage.Also,the selectivity of halophytes to different water and salt conditions should be considered in the construction of halophytes,so that the benefits of dry drainage can be unified with the ecological and economic benefits of halophytes.This paper proves that halophytes have the potential to improve the efficiency of dry drainage in wasteland,and proposes a method for the construction of halophytes in dry drainage system,which provides technical basis for the design of dry drainage project.